Amorphous Carbon Coated Silicon Nanotips Fabricated by MPCVD Using Anodic Aluminum Oxide as the Template

We have used nanoporous anodic aluminum oxide (AAO) as a template to fabricate amorphous carbon (a-C) coated silicon nanotips by microwave plasma chemical vapor deposition (MPCVD). During the preparation of the well-ordered AAO pore channel array, an underlying TiN layer was anodically oxidized as well in the late stage of the AAO anodization, forming titanium oxide nanomasks for Si nanotip fabrication. The titanium oxide nanomasks were then used to transfer the arrangement pattern of the AAO pore channel array to the Si substrate by plasma etch in the MPCVD system and, therefore, a well-ordered Si nanotip array was produced. An α-C layer ∼5 nm thick was in situ deposited on the Si nanotips during the MPCVD process. The α-C layer was rich in nanocrystalline graphitic carbons according to Raman and Auger electron spectroscopies. The nanocrystalline graphitic carbons in the coating and the sharp tip shape made the Si nanotip a good field emitter and a field enhancement factor.